Loans and Leases - Outstanding Principal Balance and Related Carrying Amount of Loans Acquired in VIST Acquisition (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Total Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding principal balance	$ 3,604	$ 6,308
Carrying amount	3,471	5,625
VIST | Acquired Credit Impaired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding principal balance	14,337	26,237
Carrying amount	11,962	22,517
VIST | Acquired Non-Credit Impaired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding principal balance	301,128	375,471
Carrying amount	298,615	371,594
VIST | Total Acquired Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding principal balance	315,465	401,708
Carrying amount	$ 310,577	$ 394,111